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TROPICAL STORM KAREN DISCUSSION NUMBER 3
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SAT OCT 13 2001
EARLY MORNING SATELLITE IMAGERY SHOWS A MARKED INCREASE IN
CONVECTION NEAR THE CENTER OF SUBTROPICAL STORM ONE....WITH TOPS
COLDER THAN -60C PRESENT FOR THE LAST SEVERAL HOURS. DVORAK
TROPICAL CYCLONE INTENSITY ESTIMATES ARE NOW EQUAL TO THE HEBERT-
POTEAT SUBTROPICAL INTENSITY ESTIMATES. ON THIS BASIS...THE
SUBTROPICAL STORM IS UPGRADED TO TROPICAL STORM KAREN. THE
MAXIMUM SUSTAINED WINDS WIL REMAIN AT 55 KT IN AGREEMENT WITH
THE SATELLITE ESTIMATES.
THE INITIAL MOTION IS NOW 035/8. KAREN IS IN AN AREA OF DEEP-LAYER
SOUTHWEST TO SOUTH-SOUTHWEST FLOW BETWEEN A RIDGE OVER THE CENTRAL
ATLANTIC AND STRONGER FLOW ASSOCIATED WITH STRONG TROUGHING OVER THE
UNITED STATES. THEREFORE...KAREN SHOULD CONTINUE ON A GENERAL
NORTH-NORTHEAST TO NORTHEAST TRACK WITHOUT A LOT OF ACCELERATION.
NHC HURRICANE GUIDANCE GENERALLY AGREES WITH THIS SCENARIO...WITH
ABOUT A NORMAL SPREAD IN DIRECTION AND SPEED. THE TRACK FORECAST
IS BASICALLY AN UPDATE OF THE PREVIOUS FORECAST...ADJUSTED SOMEWHAT
TO THE EAST TO ALLOW FOR THE NEW INITIAL POSITION.
KAREN IS OVER 25C WATER AND SHOULD REMAIN OVER SIMILAR SEA SURFACE
TEMPERATURES UNTIL IT CROSSES THE GULF STREAM. INTENSITY FORECAST
GUIDANCE CALLS FOR LITTLE CHANGE IN STRENGTH WHILE THE CYCLONE IS
OVER WARM WATER...FOLLOWED BY WEAKENING OVER THE COLDER WATER NORTH
OF THE GULF STREAM. THE INTENSITY FORECAST WILL FOLLOW THE
GUIDANCE. THERE IS A CHANCE THAT KAREN COULD REACH HURRICANE
STRENGTH IF THE CONVECTION WRAPS AROUND THE FORMER CLEAR CENTER TO
FORM A TRUE EYE.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/0900Z 35.2N 65.0W 55 KTS
12HR VT 13/1800Z 36.3N 64.4W 55 KTS
24HR VT 14/0600Z 37.8N 63.6W 55 KTS
36HR VT 14/1800Z 39.6N 62.5W 50 KTS
48HR VT 15/0600Z 41.5N 60.8W 40 KTS
72HR VT 16/0600Z 44.5N 58.5W 30 KTS...EXTRATROPICAL
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